Spaces:
Runtime error
Runtime error
File size: 5,259 Bytes
a8c8bc6 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 |
# Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
#
# NVIDIA CORPORATION and its licensors retain all intellectual property
# and proprietary rights in and to this software, related documentation
# and any modifications thereto. Any use, reproduction, disclosure or
# distribution of this software and related documentation without an express
# license agreement from NVIDIA CORPORATION is strictly prohibited.
"""Perceptual Path Length (PPL) from the paper "A Style-Based Generator
Architecture for Generative Adversarial Networks". Matches the original
implementation by Karras et al. at
https://github.com/NVlabs/stylegan/blob/master/metrics/perceptual_path_length.py"""
import copy
import numpy as np
import torch
from . import metric_utils
#----------------------------------------------------------------------------
# Spherical interpolation of a batch of vectors.
def slerp(a, b, t):
a = a / a.norm(dim=-1, keepdim=True)
b = b / b.norm(dim=-1, keepdim=True)
d = (a * b).sum(dim=-1, keepdim=True)
p = t * torch.acos(d)
c = b - d * a
c = c / c.norm(dim=-1, keepdim=True)
d = a * torch.cos(p) + c * torch.sin(p)
d = d / d.norm(dim=-1, keepdim=True)
return d
#----------------------------------------------------------------------------
class PPLSampler(torch.nn.Module):
def __init__(self, G, G_kwargs, epsilon, space, sampling, crop, vgg16):
assert space in ['z', 'w']
assert sampling in ['full', 'end']
super().__init__()
self.G = copy.deepcopy(G)
self.G_kwargs = G_kwargs
self.epsilon = epsilon
self.space = space
self.sampling = sampling
self.crop = crop
self.vgg16 = copy.deepcopy(vgg16)
def forward(self, c):
# Generate random latents and interpolation t-values.
t = torch.rand([c.shape[0]], device=c.device) * (1 if self.sampling == 'full' else 0)
z0, z1 = torch.randn([c.shape[0] * 2, self.G.z_dim], device=c.device).chunk(2)
# Interpolate in W or Z.
if self.space == 'w':
w0, w1 = self.G.mapping(z=torch.cat([z0,z1]), c=torch.cat([c,c])).chunk(2)
wt0 = w0.lerp(w1, t.unsqueeze(1).unsqueeze(2))
wt1 = w0.lerp(w1, t.unsqueeze(1).unsqueeze(2) + self.epsilon)
else: # space == 'z'
zt0 = slerp(z0, z1, t.unsqueeze(1))
zt1 = slerp(z0, z1, t.unsqueeze(1) + self.epsilon)
wt0, wt1 = self.G.mapping(z=torch.cat([zt0,zt1]), c=torch.cat([c,c])).chunk(2)
# Randomize noise buffers.
for name, buf in self.G.named_buffers():
if name.endswith('.noise_const'):
buf.copy_(torch.randn_like(buf))
# Generate images.
img = self.G.synthesis(ws=torch.cat([wt0,wt1]), noise_mode='const', force_fp32=True, **self.G_kwargs)
# Center crop.
if self.crop:
assert img.shape[2] == img.shape[3]
c = img.shape[2] // 8
img = img[:, :, c*3 : c*7, c*2 : c*6]
# Downsample to 256x256.
factor = self.G.img_resolution // 256
if factor > 1:
img = img.reshape([-1, img.shape[1], img.shape[2] // factor, factor, img.shape[3] // factor, factor]).mean([3, 5])
# Scale dynamic range from [-1,1] to [0,255].
img = (img + 1) * (255 / 2)
if self.G.img_channels == 1:
img = img.repeat([1, 3, 1, 1])
# Evaluate differential LPIPS.
lpips_t0, lpips_t1 = self.vgg16(img, resize_images=False, return_lpips=True).chunk(2)
dist = (lpips_t0 - lpips_t1).square().sum(1) / self.epsilon ** 2
return dist
#----------------------------------------------------------------------------
def compute_ppl(opts, num_samples, epsilon, space, sampling, crop, batch_size):
vgg16_url = 'https://api.ngc.nvidia.com/v2/models/nvidia/research/stylegan3/versions/1/files/metrics/vgg16.pkl'
vgg16 = metric_utils.get_feature_detector(vgg16_url, num_gpus=opts.num_gpus, rank=opts.rank, verbose=opts.progress.verbose)
# Setup sampler and labels.
sampler = PPLSampler(G=opts.G, G_kwargs=opts.G_kwargs, epsilon=epsilon, space=space, sampling=sampling, crop=crop, vgg16=vgg16)
sampler.eval().requires_grad_(False).to(opts.device)
c_iter = metric_utils.iterate_random_labels(opts=opts, batch_size=batch_size)
# Sampling loop.
dist = []
progress = opts.progress.sub(tag='ppl sampling', num_items=num_samples)
for batch_start in range(0, num_samples, batch_size * opts.num_gpus):
progress.update(batch_start)
x = sampler(next(c_iter))
for src in range(opts.num_gpus):
y = x.clone()
if opts.num_gpus > 1:
torch.distributed.broadcast(y, src=src)
dist.append(y)
progress.update(num_samples)
# Compute PPL.
if opts.rank != 0:
return float('nan')
dist = torch.cat(dist)[:num_samples].cpu().numpy()
lo = np.percentile(dist, 1, interpolation='lower')
hi = np.percentile(dist, 99, interpolation='higher')
ppl = np.extract(np.logical_and(dist >= lo, dist <= hi), dist).mean()
return float(ppl)
#----------------------------------------------------------------------------
|